1989 Edition

Cryptovolcanic structure

Reference work entry

The term cryptovolcanic structure has been used for complexes of approximately circular cross-section, superficially like volcanic pipes (necks) but containing little or no volcanic material. Limiting dimensions are not normally included in the definition but most of the bodies for which the term has been used are at least 2 km in diameter. The rocks in similar but smaller bodies, circular pipes, or bodies with irregular cross-section (even dyke-like) have been called intrusivetuffs. The large masses show signs of central uplift consisting of broken-up and contorted strata surrounded by a ring-shaped depression (rim syncline) that may be bounded or cut by faults. The whole structure often makes a topographical basin. Frequently a zonal form is recognized by the type and distribution of the fragmented material; marginal zones are made up of local wall rock, but central parts commonly consist of blocks of exotic material, mostly derived from deeper levels. The matrix typically consists...

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  1. Bowes, D. R. and A. E. Wright, 1967, The explosion-breccia pipes near Kentallen, Scotland, and their geological setting, Trans. R. Soc. Edinburgh 67, 109–143.Google Scholar
  2. Bucher, W. H., 1963, Cryptoexplosion structures caused from without or from within the Earth? (“Astroblems” or “geoblemes”?), Am. J. Sci. 261, 597–649.CrossRefGoogle Scholar
  3. Coe, K., 1966, Intrusive tuffs of west Cork, Q. J. Geol. Soc. London 122, 1–18.CrossRefGoogle Scholar
  4. Dawson, J. B., 1980, Kimberlites and their Xenoliths. New York: Springer-Verlag.Google Scholar
  5. Francis, E. H., 1960, Intrusive tuffs related to the Firth of Forth volcanoes, Trans. Edinburgh Geol. Soc. 18, 32–50.Google Scholar
  6. Reynolds, D. L., 1954, Fluidization as a geological process, and its bearing on the problem of intrusive granites, Am. J. Sci. 252, 577–613.CrossRefGoogle Scholar
  7. Roddy, D. J., R. O. Pepin, and R. B. Merrill, eds., 1977, Impact and Explosion Cratering: Planetary and Terrestrial Implications. New York: Pergamon.Google Scholar


  1.  Astrobleme;  Breccia pipe; Calderas and volcano-tectonic depressions;  Diatreme;  Fluidization;  Shock metamorphism;.

Copyright information

© Van Nostrand Reinhold 1989

Authors and Affiliations

  • K. Coe

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